Electric-motor controller.



c. T. HENDERSON. ELECTRIC MOTOR CONTROLLER.

APPLICATION FILED OCT. 2.'19|3.

Patented Apr. 6, 1915.

lllll "I" uzwwzwey 1 f Y UNITED STATES PATENT OFFICE.

CLARK T. HENDERSON, F MILWAUKEE, WISCONSIN, ASSIGNOB '10 TEECUTLBBQ HAMMER MFG. 00., OF MILWAUKEE, WISCONSIN, A CORPORATION OF WIS- consnr. I

To all whom it may concern: v

Be it known that I, CLARK T. Haisnneson, a citizen of the United States, residing at Milwaukee, in the county of Milwaukee and State of Wisconsin, have'invented new and useful Improvements in Electric-Motor Controllers, of which the following is a full,

clear, concise, and exact description, refer-' ence being bad to the accompanying drawforming ,a part of this specification. his invention relates to improvements in electric motor controllers.

- ferent sorts which it is also desirable to re late in this manner.

eretofore, it has been proposed toslo down the driving motors of such machines by connectin a resistance across the motor armature,an varying this resistance. Such an arrangement is, however, wasteful of current and at the same time so reduces the torque, that the motor is easily stalled. Furthermore, in cases wheretwo or more drivingmotors are employed it is necessary to connect a resistance across each motor armature. This renders it ditlicult to .pro-

' duce a uniform speed reduction in each motor and also requires the use of numerous switches, which it is-diiiicult to coordinate so that they willperform their functions in the desired manner.

' An object of the present invention is to provide means which will rapidly anduniformly reduce the motor speed with the consumption of a minimum amount of current.

Another object of the invention is to' pro- I vide means which will rapidly reduce the motor speed without interfering with the development of sufficient torque'to prevent stalling.

Another object of theinvention is to pro videmeans which will cause a slowing down nLnc'rnIc-moTon coiv'rnonnnnv Spcciflcatlofi of Letters Patent.

Application filed October 2, 1918. Serial 110. 788,064.

, Patented Apr. 6, 1915.

motors or. dynamo electric machines, the capacities of which depend upon the condi;v

tions, and in conjunction therewith, employs means whereby one motor may be caused to exert a drag or brakingv action on the other without interfering with the development" of a sufiicient torque by'the active motorto prevent stallin In'order to demonstrate the principles of the, invention'two embodiments have been illustrated in the accompanying drawing; although it is apparent that man other at rangements may be made which all equally within the scope of the invention. 4

In the drawing--Figure 1 represents-diagrammatically. one embodiment of the invention; Fig. 2 represents diagrammaticall a modification in which'provision is ma e for reversing one of the motors." i,

Fig. 1 illustrates two motors 1 and 2 with armatures 3 and 4, connected mechanically or otherwise so as to rotate in unison. 'The motor 1 has aseries field 5 and a shunt field 6 while the motor 2' is illustrated asprovided only with a series field 7. It is ob-- vious, of course, that other suitable types of motors may be employed. The motors are supplied with current from suitable mains 8 and 9. A starting resistance 10 for motor 1 is controlled by suitable switches 11, and a starting resistance 12 for motor 2 is controlled by switches 13. These starting re-' sistances are preferably arranged to be connected in series with the respective motor.

armatures and may be short circuited ste bfy step by the-switches 11 and 13;althoug' i desired the resistances may beconnected in any other preferred manner and controlled by any means to properly perform the desired functions. Main switches 14 and 15 control the motor circuits. A switch 16 controls a cross connection between the cot 25 7 through field 7, by conductor 19, field 5,

armature 3, and resistance 10 to main 9. At

. as..." fields of the motors. A switch 17 motorsup. to full speed. The motors bein coupled together Wlll exert their combine horse-power to operate the; load. To slow down the motors the accelerating switches are first opened thereupon reintroducing resistances 10 an .12 in circuit and reducing the voltage on the motor terminals. The

switch 16 is next closed, thus short circuiting the field of motor 2 and rendering the motor inoperative. A further speed reduction is obtained by opening the'switches 14 and 15 and the switch 17. The field of motor 2 isthus connected across the line in series with the field -5 from main 8,

the same time the armature 4 is disconnected from the mains and shortTzifcuited by the local circuit through conductors'20 and 19, resistance 18, switch 17, and'resistance 12. This will produce a dynamic brakin effect on motor 2, causin "it to exert a ag on motor 1, but asthe raking circuit contains the resistances 18 and 12 1n series .the current will be small and consequently a heavy drag will not be abruptly thrown on the active motor. The braking effect of motor 2 may be further increased by cutting out steps of resistance 12. Inasmuch as the active motor 1 is free to takecurrent from the line in accordance with the voltage across 'its'armature a torque will be maintained am leto take care of any additional load which may be imposed upon the mo- Fig. 2 illustrates a s... similar to that illustratedin Fig. 1. In this fire, however, a reversing switch is provit whereby the compound motor 1 may be operated in either direction." 1 versal of motor 1 is efiected by m or switches 21 and 22; which control the direction of current throuthe armature in the customary manner. wen the motor 1 is reversed the motor 2 exerts a drag thereon to prevent its speed becoming too" gnu might be the case, for example, in lowering a load with hoisting machinery.

As the reprtation of both systems is purely diagrammatic no attempt has been made to illustrate the actual construction of the as. In practice .and to be brought to this low y pret- Y ins-1,190

erably be electro-magnetically operated and controlled by means of a master controller.

The improved controller system themotors-to be slowed down rapi' smoothl without an undue waste. 0 rent an without reducing the torqueofthe active motor below thatrequired to-o crate the load under all conditions. It enab es the motor to be operated at a .very low speed quickly from the full running d.

In practice, the load conditi ns vary. Thus at times the normal load may besmall and at other times it may be large; Varying load conditions will be automaticall taken care of by the controller which will slow down the motors uniformly. This is due to the fact that any tendency of the active motor to slow down more quickly with a has load or less uickly with a li ht load will counters by a correspon ing difference in drag exerted by the braking meduction in t a speed of said motors.

2. In combination, a plurality of motors, normally coacting to jointly [supply a curspeed very 1 1st What I'clai lnas new and desire to secure J ofelectric I I power and means for causing one motor to exert a dra on the other for efiectmg a reelectric I 1 as power, means connecting the rotors of said motors-to'insure operation thereof in unison and means for causing one offsaxd motors to exert throu b said former'means a dra on the other 0 said motors for slowing own said motors.

3. In combination, a plurality of driving J) motors, series fields therefor, means for causing the "rotors of said motors to rotate in unison, means for connecting said series fields in series with each other and a dynamic brake for one of said motors whereby said motor may cause a uniform reduction in the of said motors regardless of load conditions.

. 4. In combination, a plurality of motors,

the rotors of which are connected together,

and means for slowingdown said motors,

mid means including means for connectin the fields of said motors in series with eac other, and means for closing a local pircuit includi a resistance around the a ture of one 0 said motors.

5. In combination, a plurality of motors,

the rotors or which are ooted to rotate M1. 2 V one motor acr a source of supply indefor connecting the field of pendently of e iature of said motor,

and means for-cl a dynamic bg circuit around. said a e a 11 r c ty a? as 7. In combination, a plurality of motors connected in arallel, means for causing the rotors of said motors to rotate in unison, a short circuit includinga resistance adapted to be completed around the armature of one motor, means for completing said circuit, and means for connectin the fields of said motors in series'with see other.

8. In combination, a' plurality of motors connected in parallel, mechanical connections between the rotors of said motors, a resistance adapted to be connected in series with the armature of one of said motors,

means for connecting said resistance in local circuit with the armature of said motor, and means for connecting the fields of said plurality of motors in Series with each other. 9.,In combination, a plurality of motors connected in parallel, a series field for each motor, a startingresistance for each motor, means for causing the rotors of said motors to rotate together, means for connecting said series fields in series with each other andwith the armature of one of said motors.

.means for disconnecting the armatureof another of'said motors from the line, and

means for connecting the armature of said last mentioned motor in a local circuit including a resistance.

1 0. In combination, a plurality of motors connected in parallel, a series field for each motor, a starting resistance for each motor, means for causing the rotors of said motors to rotate together, means for connecting said series fields in series with each other and with the armature of one of said motors, means for disconnecting the armsture of another of said motors from the line, means for connecting the armature of said last mentioned motor in a local circuit ineluding a resistance, said resistance.

11. In combination, a compound wound motor, a series motor connected in parallel therewith, means'for causing the armaturesof said motors to rotate together, means for and means for varying tor from the line connecting the field of said series motor in series with the series field of said compound motor, means for disconnecting the armature of said series motor from the line, and

,means for connecting said last' mentioned armature in local circuit with. a resistance.

12. In combination, a pair of motors, connected in parallel across supply mains, series fields for said motors, a starting resistance. for each motor, meansfor varying said resistance, means for disconnecting one field from the line and connecting the same in series with the other field, means for dis connecting the armature corresponding to said disconnected field from the line, a resistance, and means for connecting saidresistance, said disconnected armature, and its starting resistance in local circuit.

13. In combination, a. motor, a second motor connectedin parallel therewith, series fields for said motors, means for causing the armatures of said motors to rotate together, and means for reversing the armature current in one of said motors, independently of the other of said motors for the purpose set forth.

14. In combination, a motor, a. second motor connected in parallel therewith, series fields for said motors, means for connecting the armatures of said motors to rotate together, means for reversing the armature current in said first motor, means for connecting the series fields of said motors in series with each other, and means for disconnecting the armature of said second moand connecting the same in local circuit with a resistance.

15. In combination, a motor, a second motor connected in parallel therewith, series fields for said motors, means for connecting the armatures of said motors to rotate together, means for reversing the armature current in said first motor, means for connecting the series fields ofsaid motors in series with each other, and means for disconnecting the armature of said second motor from the line and connecting the same 1n local circuit with a variable resistance. 'In witness whereof, I have hereunto subscribed my name in the presence of two witnesses.

CLARK T. HENDERSON. 1 Witnesses:

FRANK H. HUBBARD, Jmnm'm S. Baocx. 

